The present invention relates generally to printing presses and more particularly to a device and a method for guiding a travelling web.
In a web-fed printing press, e.g. an offset lithographic printing press, one or more material webs, e.g. paper webs, are printed by respective print couples of printing units with different colors and are then fed to a folding apparatus for creating folded signatures. A folding apparatus typically comprises a superstructure in which a plurality of angle bars or turning bars are located and guide the paper webs from the printing units to the former boards of the folding apparatus. The angle bars can be air loaded with compressed air, which exits the angle bars through air nozzles, located in the surface of the angle bars and can also be coated with a chromium surface. Both the pressurized air and the coated surface reduce the friction of the angle bar surface and therefore marking of the freshly printed paper webs. For better access, the angle bars can be cantilevered in the superstructure of the folding apparatus.
The angle bars are used for offsetting and turning a guided travelling web or longitudinally cut ribbons of the web. A delivered portion of the web can be laterally offset with respect to an arriving portion of the web by the use of two parallel angle bars. The web can therefore be shifted for example from one side of the machine to the other side of the machine. The delivered portion of the web can also be turned with respect to the arriving portion of the web by the use of two parallel angle bars and an additional deflection roller, which is located between the two angle bars in direction of the web path.
The afore-mentioned angle bar arrangements are also used for bringing together and superposing printed paper webs before the webs are fed to a common former board of the folding apparatus.
U.S. Pat. No. 5,108,022 discloses a universal web turning system, particularly for printed webs derived from a rotary web-type printing machine. The turning system comprises a first and a second turning bar and a first and a second deflection roller which are retained in an essentially rectangular frame, with the position of the turning bars adjustable along the sides of the frame and the position of the deflection rollers being longitudinally adjustable along the sides of the frame as well as height-adjustable perpendicular to the plane of the web travelling between the respective turning bars and deflection rollers. The turning system allows for turning, offsetting or turning and offsetting a web of material especially a printed web.
For adjusting the print-to-cut register known devices are provided with an additional movable compensator roller, which by its movement changes the length of the paper path, and therefore also the print-to-cut register. U.S. Pat. No. 5,108,022 does not disclose how to adjust the print-to-cut register.
The device of the ""022 U.S. patent has a disadvantage in that at least three guiding elements, the two turning bars and at least one additional deflection roller, are needed to provide the turning system with the necessary guiding characteristics.
An object of the present invention is to provide for a reliable and efficient device for guiding a travelling web, which comprises few movable components for achieving the necessary guiding characteristics.
The present invention provides a device for guiding a travelling web comprising:
a first movable angle bar and a second movable angle bar;
the first movable angle bar being located in a position P1 and the second movable angle bar being located in a position P2 in a first operative mode to guide the travelling web from an entering direction D1 to an exiting direction D2 and to define a first print-to-cut registration setting;
the first movable angle bar being located in a position P3 and the second movable angle bar being located in a position P4 in a second operative mode to guide the travelling web from the entering direction D1 to an exiting direction D3, the exiting direction D3 being offset with respect to the exiting direction D2, the second operative mode having the first print-to-cut registration setting; and
the first movable angle bar being located in a position P5 and the second movable angle bar being located in a position P6 in a third operative mode to guide the travelling web from the entering direction D1 to the exiting direction D2, the third operative mode having a second print-to-cut registration setting.
The terms P1 to P13 and D1 to D4 in this application are used herein solely to distinguish the positions and direction from one another, and are not meant to have any specific meaning. The operative modes may also be called operative conditions.
The present invention permits guiding of a travelling web, particularly shifting the exiting direction of the travelling web and permits adjusting the print-to-cut registration setting with only two movable angle bars. It is an advantage of the present invention that the number of movable components is reduced to only two movable angle bars without the need of further compensator rollers and that therefore a cost and maintenance reduction can be achieved.
It is possible to change, i.e. to move or locate the respective angle bars, from the first operative mode to the second or the third operative mode or to change from the second operative mode to the third operative mode. Also returning to the first operative mode is possible from the second or the third operative mode is possible.
In a further embodiment of the invention the device comprises at least one first movable device being operative for moving the first movable angle bar and at least one second movable device being operative for moving the second movable angle bar.
Preferably, at least one of the first and second movable angle bars is pivotable.
In a preferred embodiment of the invention at least one of the first and second movable devices is a sliding carriage and at least one of the first and second movable angle bars is pivotably mounted on the respective movable device. The sliding carriage provides a linear movement, preferably substantially perpendicular to the direction of the arriving portion of the travelling web, and by mounting the angle bars pivotally on the respective sliding carriages also a rotational movement can be provided and can be superposed with the linear movement of the sliding carriage.
It is further possible and in certain cases even advantageous to support at least one of the first and second movable angle bars by means of pistons, which are slidably supported by the sliding carriage, i.e. for example by a base body of the sliding carriage.
It is also possible that at least one of the first and second movable angle bars is pivotably mounted with both ends to one of the respective movable devices.
In accordance with another feature of the invention, the device further comprises at least one further guiding element, e.g. a third bar or a first deflection roller, located between the first angle bar and the second angle bar on the path of the travelling web, the further guiding element guiding the web from the first angle bar to the second angle bar thereby turning the web. The axis of the further guiding element, e.g. of the third bar can be located substantially parallel to the direction of the arriving portion of the guided web. Further, it is possible that the further guiding element of the device is movable.
A device according to the invention can also comprise two further guiding elements, e.g. a third and a fourth bar located between the first angle bar and the second angle bar on the path of a travelling web, the third and the fourth bar located one above the other, in order to guide the travelling web from a lower angle bar unit to an upper angle bar unit. This advantageously allows for feeding multiple-color pages to any part of a newspaper in a press with limited color capability.
All the movements of the angle bars, bars or deflection rollers can be performed manually or automatically.
In accordance with another feature of the invention, the device further comprises a control device for controlling an automatic movement of at least one of the first and second movable angle bars in e.g. at least one of the second and third operative modes. The control device allows for an automatic change or location of the movable angle bars from one position to another position e.g. by activating or driving the at least one first and second movable devices being operative for moving the respective first and second movable angle bars. This advantageous embodiment also allows for a remote setting of the angle bars, e.g. when a registration adjustment is necessary because the water content of the web effected a misregistration.
In accordance with an additional feature of the invention, the control device calculates the movement of at least one of the first and second movable angle bars dependent on the entering direction D1, the exiting direction D2, the exiting direction D3 and the first print-to-cut registration setting. The calculation can be performed in the first operative mode and the calculated position changes can be used to move the first and the second angle bars to respective positions in the second operative mode.
In accordance with another feature of the invention the control device calculates the movement of at least one of the first and second movable angle bars dependent on the entering direction D1, the exiting direction D2, the first print-to-cut registration setting and the second print-to-cut registration setting. It is advantageous to calculate the position changes of the first and second movable angle bars in the first operative mode and to use the calculated position changes or calculated new positions to achieve the third operative mode by locating the movable angle bars in their respective positions, which define the third operative mode or condition.
According to another exemplary embodiment of the invention, the control device calculates the movement of at least one of the first and second movable angle bars dependent on the distance between a first reference point of the path of the travelling web located upstream of the first angle bar and a second reference point of the path of the travelling web located downstream of the second angle bar.
In a first embodiment the control device can calculate the movement of at least one of the first and second movable angle bars without changing the distance between the two reference points, so that the first print-to-cut registration setting is maintained, whereas in a second embodiment the control device can calculate the movement of at least one of the first and second movable angle bars with a defined change in the distance between the first and second reference points to change to a second print-to-cut registration setting.
In a further embodiment of the invention the device further comprises at least one driving device, for example an electric motor or a stepping motor, for the movement of the respective movable device of at least one of the movable angle bars. The at least one driving device may be controlled by the control device.
It is also possible, that the different positions, i.e. the coordinates of the positions, are stored in storing device, e.g. a harddisc, after being calculated and are loaded from the storing device into the control device for controlling the locations or movement of the different angle bars, bars or rollers.
Further, in an advantageous embodiment of the present invention, at least one of the first and second movable angle bars is air loaded, for example with pressurized air. It is also possible that at least one of the first and second movable angle bars is provided with a low friction surface, for example a chromium coated surface, which can also be polished.
In accordance with another feature of the present invention at least one of the exiting directions of the delivered portion of the travelling web or the longitudinally cut ribbons of the printed web is parallel to the entering direction of the arriving portion of the travelling web or the longitudinally cut ribbons of the printed web. By the use of additional deflection bars or deflection rollers the exiting direction of the travelling web can be changed to any desired direction and the orientation of the exiting direction can also be opposite to the entering direction of the travelling web.
According to another advantageous embodiment of the present invention the first movable angle bar is located in a position P7 and the second movable angle bar is located in a position P8 in a fourth operative mode or condition to guide the travelling web from the entering direction D1 to an exiting direction D4, the exiting direction D4 being offset with respect to the exiting direction D2, and the fourth operative mode having a third print-to-cut registration setting.
According to another embodiment of the invention, the device for guiding a travelling web comprises a first movable angle bar and a second movable angle bar, the first movable angle bar being located in a position P1 and the second movable angle bar being located in a position P2 in a first operative mode to guide the travelling web from an entering direction D1 to an exiting direction D2 and to define a first print-to-cut registration setting, the first movable angle bar being located in a position P7 and the second movable angle bar being located in a position P8 in a fourth operative mode to guide the travelling web from the entering direction D1 to an exiting direction D4, the exiting direction D4 being offset with respect to the exiting direction D2, the fourth operative mode having the third print-to-cut registration setting
An embodiment of the invention comprising a fourth operative mode allows for simultaneously changing the exiting direction of the travelling web and the print-to-cut registration setting. It is possible to change from the first operative mode to the fourth operative mode or to return from the fourth operative mode to the first operative mode. The above-mentioned control device can also control the automatic movements of the angle bars in the fourth operative mode.
A further embodiment of the invention provides that the first movable angle is located in a position P9 and the second movable angle bar is located in a position P10 in a parking operative mode to park the first and second movable angle bars, e.g. for operator access. The parking position advantageously eliminates the need for removing the angle bars for better access.
In a further embodiment of the present invention the first movable angle bar is located in a position P11 and the second movable angle bar is located in a position P12 in a web up operative mode to thread a web through the device.
The device according to the present invention also allows for moving the two movable angle bars into the web-up position, for forwarding a web through the open space between the angle bars and to relocate the two angle bars into their respective guiding positions without locating the two angle bars at an angle to the travelling direction of the web. The web is thereby guided from the entering direction to the exiting direction without a lateral web shift. The web therefore runs straight through the angle bar unit without using the angle bars for offsetting the exiting portion of the web with respect to the entering portion of the web, which allows totally automated web-up performance.
It is also possible to combine the parking operative mode and the web-up operative mode in one operative mode of the inventive device.
The first movable angle bar can also be located in a position P13 in a fifth operative mode to accommodate the entering direction D1 of the travelling web in accordance with another embodiment of the present invention. This movement, which can also be controlled by above-mentioned control device, allows e.g. the correct positioning of the first angle bar when a lateral offset of the printed paper web has been performed particularly in a two or more web width printing press.
The present invention also provides a method for guiding a travelling web comprising the following steps:
locating a first movable angle bar in a position P1, locating a second movable angle bar in a position P2, guiding the travelling web from an entering direction D1 to an exiting direction D2 and defining a first print-to-cut registration setting;
moving the first movable angle bar into a position P3, moving the second movable angle bar into a position P4, thereby maintaining the first print-to-cut registration setting, and guiding the travelling web from the entering direction D1 to an exiting direction D3, the exiting direction D3 being offset with respect to the exiting direction D2; and
moving the first movable angle bar into a position P5, moving the second movable angle bar into a position P6, thereby maintaining the exiting direction D2 and changing to a second print-to-cut registration setting.
The method according to the invention allows for a simple change of the exiting direction of the travelling web or a simple change of the print-to-cut registration setting only by moving the first and second movable angle bars.
The present invention further provides a method for guiding a travelling web, comprising the following steps:
locating a first movable angle bar in a position P1, locating a second movable angle bar in a position P2, guiding the travelling web from an entering direction D1 to an exiting direction D2 and defining a first print-to-cut registration setting;
moving the first movable angle bar into a position P7, moving the second movable angle bar into a position P8, thereby changing to a third print-to-cut registration setting, and guiding the travelling web from the entering direction D1 to an exiting direction D4, the exiting direction D4 being offset to the exiting direction D2.
This method according to the invention provides a simple and simultaneous change of the exiting direction of the travelling web and of the print-to-cut registration setting.